Field
The present disclosure relates to a substrate for an organic light emitting display device with improved light extraction efficiency and an organic light emitting display device.
Description of the Related Art
In recent years, an organic light emitting display device which has gotten the limelight as a display device has an advantage in that a response time is high, and contrast ratio, emission efficiency, brightness, and a viewing angle are large by using an organic light emitting diode (OLED) having a self-luminance characteristic.
Light emitted from an organic emission layer of the organic light emitting display device passes through various constituent elements of the organic light emitting display device to be discharged to the outside of the organic light emitting display device. However, light which is not discharged to the outside of the organic light emitting display device, but blocked in the organic light emitting display device among the light emitted from the organic emission layer is present and thus, there is a problem in light extraction efficiency of the organic light emitting display device with respect to the front and the side of the organic light emitting display device.
Further, since an optical path length of light emitted from the organic light emitting diode having a flat plane differs with respect to the viewing angle, a color change with respect to the viewing angle occurs and a color shift for red (R), green (G), and blue (B) colors increases, and as a result, chromaticity characteristics become vulnerable on the side.
Accordingly, a scheme that can solve the problem is required.
A substrate for forming an organic emission layer may include a protective layer for flattening a step due to formation of a transistor, an anode electrode formed on the protective layer, and a bank layer formed in an area other than an area for emission. In addition, the organic emission layer is laminated on the flat anode electrode, and as a result, the organic emission layer is also formed in a flat form. Since the flat emission surface significantly depends on an optical path length with respect to a viewing angle, a color change according to a viewing angle of an organic light emitting display device occurs, and as a result, it is characterized that the flat emission surface is vulnerable to a color shift on a side. Further, when an inclination angle is given to an opening of the bank layer in the related art, an amount of some light of a light emitting unit hits and is reflected on an inclination surface of the bank layer, and the amount of a collected light on a front is also small.
In addition, the color shift which occurs on the side of the organic light emitting display device means red, green, and blue color shifts and a white color shift with respect to a viewing angle and since the color shift which occurs on the side increases on the flat emission surface, color shift characteristics are vulnerable on the side. In this case, the color shift may mean a difference in color coordinate with respect to a viewing angle.